The National Telecommunications and Information Administration (NTIA) is now officially taking applications for DTV converter coupons.This is the voucher website.

Please be aware that these vouchers are for boxes that will convert digital signal to analog.  These do not deliver full HDTV, but instead make DTV compatible with older TV sets.

These boxes are not designed for use with cable or satellite systems.  Your cable company or satellite provider will provide (and most likely, already has provided) a box compatible with their system.

According to the best info I can gather, the first 22 million applications will be processed automatically.  After that the NTIA will use their discretion.  It is generally assumed the full allotment of 44 million vouchers (2 per household) will not be used.  In case where preference needs to be given, it will be given to households that get their TV solely over-the-air (as opposed to households that might just have an upstairs TV with an antenna, while the living room TV has cable).
The program was paid for through fees collected by the government during the auction of upper UHF spectrum channels to various companies, so please don’t feel as if it is a subsidy or a handout.  The airwaves belong to the people, and this is the government defraying some of the cost of the inconvenience imposed.